I'm trying to prove that a=a* and b=b* using only the fact that the sum of the interior angles of a triangle is 180 degrees.
In my diagram, there are 2 triangles: ABC and A*B*C
a + b + c = 180 and a* + b* + c =180 (a,b,a*,b,c are angles)
since both equations equal to 180, I equate them to each other and subtract angle c from both sides to get:
a + b = a* + b*.
I'm stuck here. I proved that their sum is the same, but not the angles. Do you have any suggestions?
What if I didn't know that the two lines were parallel?
What I'm tring to prove is that angles are congruent (using only the fact that the sum of the interior angles is 180). Would you know how?
I started what I thought was the correct method (my earlier post), but got stuck.